Use the psalm executable with the LS option

This is the simplest way of getting the psalm language server to run
now.

ale_linters/php/psalm.vim

@@ -1,7 +1,7 @@
 " Author: Matt Brown <https://github.com/muglug>
 " Description: plugin for Psalm, static analyzer for PHP
 
-call ale#Set('psalm_langserver_executable', 'psalm-language-server')
+call ale#Set('psalm_langserver_executable', 'psalm')
 call ale#Set('psalm_langserver_use_global', get(g:, 'ale_use_global_executables', 0))
 
 function! ale_linters#php#psalm#GetProjectRoot(buffer) abort
@@ -14,8 +14,8 @@ call ale#linter#Define('php', {
 \   'name': 'psalm',
 \   'lsp': 'stdio',
 \   'executable': {b -> ale#node#FindExecutable(b, 'psalm_langserver', [
-\       'vendor/bin/psalm-language-server',
+\       'vendor/bin/psalm',
 \   ])},
-\   'command': '%e',
+\   'command': '%e --language-server',
 \   'project_root': function('ale_linters#php#psalm#GetProjectRoot'),
 \})

test/command_callback/test_psalm_command_callbacks.vader

@@ -9,18 +9,18 @@ After:
   call ale#assert#TearDownLinterTest()
 
 Execute(The default executable path should be correct):
-  AssertLinter 'psalm-language-server',
-  \ ale#Escape('psalm-language-server')
+  AssertLinter 'psalm',
+  \ ale#Escape('psalm') . ' --language-server'
 
 Execute(Vendor executables should be detected):
   call ale#test#SetFilename('psalm-project/test.php')
 
   AssertLinter
-  \ ale#path#Simplify(g:dir . '/psalm-project/vendor/bin/psalm-language-server'),
+  \ ale#path#Simplify(g:dir . '/psalm-project/vendor/bin/psalm'),
   \ ale#Escape(ale#path#Simplify(
   \   g:dir
-  \   . '/psalm-project/vendor/bin/psalm-language-server'
-  \ ))
+  \   . '/psalm-project/vendor/bin/psalm'
+  \ )) . ' --language-server'
 
 Execute(The project path should be correct for .git directories):
   call ale#test#SetFilename('psalm-project/test.php')